1. Technical Field
The present invention generally relates to systems and methods for cleaning food and food processing equipment, and more particularly, to a surface microbial intervention system and method that provide a 5-log (i.e., 100,000 times) reduction in the amount of microbial pathogens on the surface of food products and other items, such as food processing equipment.
2. History of Related Art
Fruits, vegetables, and other foods are allowed to remain in contact with soil, insects, and animals during the time of their growth and harvest. Thus, fresh produce, for example, maintains populations of 104 and 105 microorganisms/gram when they arrive at the packing house. Such microorganisms include coliform bacteria, including Enterobacter, Klegsiella spp., and Escherichia coli. The bacteria population tends to remain relatively stable, with no significant influence exerted by temperature, total precipitation, or length of the day during harvest. Such bacteria may become natural contaminants of frozen concentrated fruit juices.
Since improperly handled food products and processing equipment can serve as a vehicle for the transmission of microorganisms to humans, the elimination of such surface bacteria and pathogenic microbes (which include spoilage organisms) has a tremendous value to the food and health industries. For example, there is currently a requirement by the Food and Drug Administration and the United States Department of Agriculture that all juice products include the following warning statement on package labels after Nov. 5, 1999.
WARNING: This product has not been pasteurized and, therefore, may contain harmful bacteria that can cause serious illness in children, the elderly, and persons with weakened immune systems.
Thus, there are not only safety hazards afforded by the presence of these surface contaminants, but also marketing and legal implications.
Several approaches to reducing the number of bacteria on the surface of produce, food products, and food processing equipment have been attempted. Common chemical sanitizers, such as chlorine treatments, may be reasonably effective for equipment sanitation, but these chemicals apparently have little effect on microorganisms. Another approach includes steaming herbs, spices, and root/tuber vegetables under pressure, or in a vacuum. Chemical gases may be used to create an antiseptic environment. Each of these processes tends to be expensive and unreliable, fraught with an abundance of complicated equipment which tends to break down, and produce unpredictable results.
Even when simple steam is applied to provide microbial intervention at the surface of food products and processing equipment, it is often the case that expensive and complicated steam generation apparatus is used. Further, the methods of steam production often involve holding times that are overly long; such immersion in steam or hot water tends to adversely affect the organoleptic properties of the food products so treated.
Therefore, what is needed, is an apparatus and method for microbial intervention and pasteurization of food product and food processing equipment surfaces which is inexpensive and mechanically simple. Further, the apparatus and method should produce repeatable, reliable results. More specifically, the holding time for the food products to be surface pasteurized should be consistently maintained at the minimum level necessary to accomplish a 5-log reduction in the amount of surface bacteria and/or microorganisms present on external surfaces of the food and processing equipment. A minimum number of steps to implement the process of such a method should be required, and preferably, no special chemicals should be introduced into the microbial intervention process.
By way of experimentation, it has been determined that the simplest method to accomplish microbial intervention at the surface of food products and processing equipment involves the use of steam and chilled water. An economically viable and mechanically robust apparatus adapted for microbial intervention and pasteurization of food product and processing equipment surfaces comprises a chamber in fluid communication with a steam generator which is in turn connected to a controller and timer, a produce temperature sensor, and a power source.
A chilled water source is present in the interior portion of the chamber, and is typically located above a suspension element (e.g., shelf or conveyor belt) which supports the produce or equipment above the bottom surface of the chamber interior. The water source provides water to bathe the produce or equipment at a (temperature from about 2xc2x0 to about 5xc2x0 C., if chilled). The source may be located in the interior portion of the chamber, or at the exterior of the chamber, depending on the particular process implemented, and the desires of the user. The water may include a sanitizing agent, including a suitable food and equipment grade sanitizer, such as chlorine, in quantities of about 50 ppm to about 400 ppm.
The steam generator has a steam pipe by which steam is conducted to the chamber. A water inlet valve allows water into the steam generator interior. The water inlet valve is in fluid communication with an orifice and a regulating valve, which ensures that the water volumetric flow never exceeds a preselected level.
The invention also includes a method for microbial intervention and pasteurizing the outer surface of foods and food processing equipment comprising the steps of placing the food or equipment in the chamber, adding steam to the chamber, sensing the temperature of the outer surface of the food or equipment, and adding steam to the chamber until the sensed temperature is about 74xc2x0 C. Once the temperature reaches 74xc2x0 C., a 60-second timer is started to ensure that the surface of the produce or equipment is exposed to steam for at least 60 seconds at the required temperature. After this period of time, the outer surface of the produce or equipment may be bathed with chilled water for about 60 seconds. If chilled, the temperature of the water is about 2xc2x0-5xc2x0 C.
The temperature of the food or equipment surfaces may be sensed by placing a thermocouple on the surface of the food or equipment, or by inserting the thermocouple into the food, and sensing the temperature approximately xc2xc inch below the food surface. A remote infrared sensor can also be placed or located to detect the surface temperature of the food or equipment, and used to control implementation of the method.
The chamber may be structured as a tunnel with openings at either end for the continuous pasteurization of food on a roller conveyor. In this embodiment, the steam generator is connected to three steam pipes in the steam tunnel and one steam pipe underneath the roller conveyor. These pipes have multiple outlets in order to surround the food with steam from several directions at once. As the food exits the steam tunnel, the food is sprayed with a chilled water bath from a chilled water source outside the tunnel.
The food processing equipment pasteurization system may be structured as a stainless steel bonnet or cover which is lowered over a piece of food processing equipment such as a meat slicer. The equipment sits on a bottom unit which includes a grated floor and drain pans. A steam inlet in the hood allows the steam to enter the bonnet. The steam is controlled by venting handles which allow excess pressure to escape. Steam flow is directed across the surface of the hood via multiple openings. The base unit also contains steam pipes with multiple outlets to allow steam to escape from the hood. Drain pans in the bottom unit collect steam and particles from the equipment.